This invention relates to a Korotkov sound sensor for use with an electronic sphygmomanometer for electrically discriminating Korotkov sounds.
The typical recently developed electronic sphygmomanometer has a microphone incorporated in a cuff which occludes blood flow. The blood pressure of an individual is measured when the cuff is wrapped around the arm of an individual to position the microphone over or adjacent an artery below the blood-occluding portion of a cuff.
Since the microphone for such a sphygmomanometer is disc-shaped and is positioned over the artery, positioning the microphone on the arm of an individual affects the accuracy of detecting Korotkov sounds and is a major reason for introduction of errors and difficulty in the measurement of blood pressure by inexpert persons.
Various types of Korotkov sound sensors have been developed to measure blood pressure with high sensitivity and high accuracy independent of the skill of the individual. For example, an inflatable cuff for detecting Korotkov sounds is jointly used with an inflatable cuff for occluding blood flow and a small-sized microphone is applied to the end of the pressure guide tube which is connected between the cuffs. The sound pick up area in that structure is so wide, since the microphone receives Korotkov sounds transmitted through the air in the inflatable cuff for detecting Korotkov sounds, that positioning of the microphone is not a problem. However, such structure shows a tendency to generate or pick up various noises, especially when the individual touches the cuffs or the pressure guide tube connected between the cuffs. As a result, easy and accurate measurement of blood pressure is not achieved.